1. Field of the Invention
The present invention relates generally to heat sinks and, more particularly, to an improved method for externally lowering the operational temperature of an electronic assembly and apparatus for accomplishing the same.
2. Description of Related Art
A past design practice for cooling an electronic assembly has been to directly plumb coolant into the assembly. Thereby, coolant is either statically held in reservoirs throughout the assembly or pumped through coolant channels in the assembly. Another past practice has been to provide coolant plates to which the electronic assembly is fastened. The coolant plates typically include fin elements along which the coolant passes.
In the context of integrated circuits, artisans have utilized an organic film to enclose a thermally conductive liquid of a fixed amount. The film and fixed amount of liquid are contained in a cover which encloses the chip. Thereby, a conformable heat radiator contacts the chip. This is shown, for example, in U.S. Pat. Nos. 4,323,914 and 4,092,697.
In a similar fashion, a rigid housing with a thin-wall diaphragm has been provided to enclose a coolant chamber which is securely fastened to a base which holds an integrated circuit package. Elastomeric strips are then used to bias the diaphragm and thermally conductive disks contact the individual dice in the package. This is shown in U.S. Pat. No. 4,381,032.
Each of the above approaches, however, has limitations which lessen performance. Direct plumbing requires fluid couplings for electronic assembly removal and replacement. To reduce electronic assembly removal time for servicing, direct plumbing designs have required the use of quick disconnect fittings. While generallY satisfactory connections can be accomplished with these fittings, they have the drawbacks of being expensive and allowing fluid leakage with each connection or disconnection.
Fixed coolant plates have their drawbacks. They create the need for a high degree of flatness and stiffness within the plates themselves and within the electronic assemblies for consistent and predictable thermal performance. Yet, the flatness requirement creates a situation where many high rate production processes are no longer feasible. Hence, the coolant plates and the electronic assembly chassis become very costly.
Enclosed liquid chambers that are fastened to a support to surround the assembly prevent easy assembly, removal and insertion. Removal or insertion of an electronic assembly requires removal and reattachment of the coolant chamber to the support.
A need still exists in the art to provide a heat sink that is low in cost, eliminates the need for couplings, and dissipates heat in an efficient manner.